The present invention relates to a recording medium cutter for cutting a recording medium, which is being moved, in the moving direction thereof in an image forming device for forming an image on the recording medium, such as recording paper, and also relates to an image forming device using the recording medium cutter.
Among the output devices for computers and workstations, an ink jet image forming device that ejects ink drops and forms an image on a recording paper sheet moved in a predetermined moving direction and an electrophotographic image forming device that forms an image with toner are known. In those image forming devices, the area of a large-size paper sheet is sometimes divided into half or quarter segments to efficiently arrange smaller-size images in the divided areas to thereby make waste-free use of the large-size paper sheet. In such cases, normally, after images are formed, the paper sheet is cut into the segments of the areas.
In cutting a paper sheet, there are two methods with regard to the cutting direction thereof: one is a Y-cutting (also called transverse cutting) method to cut a paper sheet in a direction perpendicular to the sheet moving direction, and the other is an X-cutting (also called longitudinal cutting) method to cut a paper Sheet in the same direction as the sheet moving direction. The X-cutting method is useful for cutting out smaller-size segments from a wide-width paper sheet or cutting the paper sheet into two half segments.
Moreover, there are manual cutting and automatic cutting for cutting a paper sheet, the latter being performed automatically in the image forming device. In the automatic cutting, when the Y-cutting method is used, after images have been formed, a Y-cutting means (a blade or blades), which is placed in position, is made to traverse in a direction perpendicular to the sheet moving direction to perform a transverse cutting. On the other hand, when the X-cutting is used, before images are formed an X-cutting means (a blade or blades) is moved and set at a cutting position in advance, and then a longitudinal cutting of the paper sheet is performed by utilizing the power of moving the paper sheet in the image formation process.
An X-cutting unit for cutting a paper sheet in the moving direction of the paper sheet is generally equipped with two disc blades, which rotate in contact with the paper sheet to cut the same.
As an example of such X-cutting unit, a connect-disconnect type cutting unit is known which has two blades such that when no X-cutting is necessary the blades are set apart to opposite positions across a paper sheet, and when the paper sheet is to be cut they are moved vertically to the positions where they come into contact with the paper sheet to cut the same.
A shift type cutting unit is also known which has two disc blades, which are in contact with each other with their mutual positional relationship kept fixed, and which are placed in a standby position in the sheet width direction away from the sheet moving path, so as not to obstruct the moving of the paper sheet. When a paper sheet is to be cut, the cutting unit is shifted from the standby position to a cutting position to cut the paper sheet.
When two such opposing blades are used for cutting, if the gap between the blades is not adequate, the cutting unit is unable to exhibit a desired cutting performance. It is known that if the gap is too wide, no cutting is achieved or the cutting section becomes unclean.
Out of the above-mentioned conventional X-cutting units, in the connect-disconnect type X-cutting unit, when the two blades are moved up or down to a position where they contact a paper sheet for cutting the same, it is difficult to adjust the positions of the two blades that are separately configured. Because of this, there may be possibilities that the two blades are not positioned a desired distance apart, and the paper sheet cannot be cut at a correct cutting position, or cannot be cut straight.
On the other hand, in the above-mentioned shift type cutting unit, the gap between the two blades can be assured, but it takes time for the X-cutting unit to be shifted to the cutting position, with the result that a long time is required before cutting. The time for shifting the cutting unit to reach the cutting position is a greater problem for a larger-size paper sheet with a broader width.
Meanwhile, Japanese Patent Publication (KOKOKU) No. Hei4-55878 (Japanese Patent Application Laid-Open (KOKAI) No. 59-164192) discloses an X-cutting unit for cutting a paper sheet in the sheet moving direction, in which one rotary blade is supported at one end of an arm, and when a paper sheet is to be cut, the rotary blade is pivoted about the other end of the arm to bring the rotary blade into contact with the paper sheet. Because this X-cutting unit is a kind of the connect-disconnect type, although there is no problem of time for the shifting, there may be a problem that the use of one cutting blade does not necessarily bring about good cutting results of the paper sheet. In addition, to drive the rotary blade and the pivotable arm independently of each other, separate drive sources (motors) are used. This results in the complexity in its structure and a high cost of the device.
Also, if a space for movement of the X-cutting unit is provided across the sheet moving path, along which a recording medium is moved, in order to change the cutting position, and if the X-cutting unit is moved in that space in a direction perpendicular to the sheet moving direction, there may be a possibility that the recording medium being moved is caught at a border portion between the space and the main body of the image forming device.
Incidentally, the cutting position in the automatic cutting is normally decided according to information about a cutout size of a paper sheet.
In the X-cutting by which to cut a paper sheet in the same direction as the sheet moving direction, there has been a problem as follows in deciding the cutting position.
Even if the cutting means is located at a fixed position previously decided according to a standard size of paper sheet to be cut out, the actual edge positions of the cut-out paper sheet are not necessarily constant because of errors in edge positions (left and right edges) of a paper sheet that has been set to be cut. As a result, there are likely to be variations in the width of the paper sheets cut out by the X-cutting means which has been set at a fixed position in a direction (sheet width direction) perpendicular to the sheet moving direction.
Some users have been desired that it should be made possible to cut a roll paper sheet or a large-size cut-sheet in accordance with the size of an image formed on the paper sheet. A possible solution to this is to manually move the X-cutting means to an estimated longitudinal cutting position based on the size of a formed image. However, large errors could occur in estimating the sizes of individual images formed on the paper sheet and manually setting the longitudinal cutting positions. It sometimes happens that the margins around an image are too large or too small.
When one wishes to make better use of recording paper by forming a plurality of images (two for example) across the width of a roll paper sheet or a large cut-sheet, it is desirable to cut the paper sheet into equal widths of segments. In such a case, there has been a problem that because the X-cutting means is set at a previously decided fixed position, as mentioned above, errors could occur due to the tolerances in paper sheet position, resulting in a low accuracy of cutting.
In view of the above-mentioned circumstances, an object of the present invention is to provide a recording medium cutter which uses two blades for the X-cutting unit, reduces time for cutting, assures that the gap between the two blades is kept at a desired value, and can perform longitudinal cutting of a recording medium at an accurate position.
A second object of the present invention is to provide a recording medium cutter which do not hamper the smooth moving of a recording medium.
A third object of the present invention is to provide an image forming device having a longitudinal cutting unit which automatically cuts a recording paper sheet, and can decide a cutting position with high accuracy.
According to the present invention, there is provided a recording medium cutter for use in an image forming device for forming an image on a recording medium moved to an image forming area, the cutter being located downstream of the image forming area in the recording medium moving direction, for cutting the recording medium being moved, the recording medium cutter comprising:
a rotary blade for cutting, while rotating, a recording medium in the moving direction thereof;
a driven blade driven by the rotary blade for cutting, while rotating, the recording medium in the moving direction thereof, in cooperation with the rotary blade;
blade holding means rotatable about a center axis of the rotary blade while rotatably holding the rotary and driven blades with a positional relationship between the two blades kept fixed; and
rotating means for rotating the blade holding means between a cutting position where the recording medium is cut and a non-cutting position where the recording medium is not cut. With this configuration, since the rotary and driven blades are positioned either in the cutting position or in the non-cutting position, the blades can be moved quickly from the non-cutting position to the cutting position, so that the time for cutting can be reduced.
Also, because the rotary and driven blades are held with their positional relationship kept fixed, the gap between the two blades can be kept fixed at a desired value, for which reason the recording medium can be cut cleanly at a correct position.
Preferably, the blade holding means includes a guide portion for guiding the recording medium when the driven blade is located at the non-cutting position. Therefore, notwithstanding the presence of the recording medium cutter, the recording medium is guided smoothly.
Preferably, the rotating means includes a single drive means for rotating the rotary blade and the blade holding means as well. In this case, the rotating means continues to rotate the rotary blade still after the blade holding means has reached the cutting position and has stopped rotating. The use of such rotating means as a common drive for the rotary blade and the blade holding means will save the required space in the device and the cost thereof.
Preferably, the rotary and driven blades respectively have center axes substantially parallel with each other, and the rotary and driven blades are pressed against each other on their side faces. With this arrangement, a segment of the medium on the rotary blade side and another segment of the medium on the driven blade side, both being cut off from a recording medium, will move in opposite directions, so that a tensile force is applied to that portion of the paper sheet being cut, and hence, the recording medium is readily cut.
The rotation of the blade holding means can be realized by the driven blade which revolves around the rotary blade as the rotary blade rotates on its axis. The recording medium cutter has first and second stopping means for stopping the rotation of the blade holding means respectively at the cutting and non-cutting positions.
Means for moving the blade holding means in a direction perpendicular to the recording medium moving direction may be provided. With this arrangement, a recording medium can be cut at an optional position in the direction perpendicular to the recording medium moving direction.
Moreover, a recording medium cutter may further comprise recording medium dividing and guiding means for guiding, out of a pair of segments of the medium cut out by the rotary and driven blades, a segment of the medium on the rotary blade side relative to a cutting point, where the rotary and driven blades come into contact with the recording medium, in a direction of going away from the center axis of the rotary blade and also guiding a segment of the medium on the driven blade side relative to the cutting point in a direction of going away from the center axis of the driven blade, the recording medium dividing and guiding means being located downstream of the cutting point in the recording medium moving direction. This will cause the segment of the medium on the rotary blade side relative to the cutting point and the segment of the medium on the driven blade side relative to the cutting point to be guided in mutually opposite directions, so that a tensile force is applied to that portion of the recording medium which is going to be cut, and therefore the recording medium is cut more easily and moved smoothly.
One of the first and second stopping means may serve also as position-detecting means for detecting a rotational position of the blade holding means.
When the recording medium cutter further includes an ejection guide plate for guiding the recording medium moving in a sheet ejecting direction, the ejection guide plate having formed therein an opening for the blade holding means to move through in a direction perpendicular to the recording medium moving direction, the recording medium cutter preferably includes a recording medium moving plate which is capable of closing that area in the opening for movement other than the area occupied by the blade holding means and which is also movable with the movement of the blade holding means. The ejection guide plate""s opening for the cutter movement comes to be closed by the recording medium moving plate as the blade holding means moves, and therefore the recording medium can be moved smoothly.
According to the present invention, there is provided an image forming device for forming an image on a recording paper sheet on the basis of image data while moving the paper sheet to an image forming section, the image forming device comprising:
paper sheet side edge detecting means for detecting the position of at least one of two side edges of the paper sheet which are parallel with a paper sheet moving direction;
transverse cutting means for cutting the paper sheet in a direction perpendicular to the paper sheet moving direction;
longitudinal cutting means for cutting the paper sheet in the same direction as the paper sheet moving direction by utilizing the moving power of the paper sheet, the longitudinal cutting means being mounted movably in a direction perpendicular to the paper sheet moving direction;
longitudinal cutting control means for moving and setting the longitudinal cutting means at a longitudinal cutting position;
image area detection means for obtaining information about an area of an image based on the image data;
transverse cutting-position deciding means for deciding a transverse cutting position according to image area information obtained by the image area detection means; and
longitudinal cutting-position deciding means for deciding a longitudinal cutting position according to information about paper sheet side edge detected by the paper sheet side edge detecting means and the image area information;
wherein the longitudinal cutting control means moves and sets the longitudinal cutting means at a longitudinal cutting position decided by the longitudinal cutting-position deciding means.
The image forming section mentioned above is means for putting some color dots on a recording paper sheet. For example, it is an ink head or a carriage in the ink jet recording system. Alternatively, it is a thermal head in the thermosensitive recording system or in the thermal transfer recording system. At least one of two side edges of a recording paper sheet denotes the side edge on the side used as a reference position when an image is formed on a paper sheet before cutting. With this configuration, longitudinal and transverse cutting positions can be decided according to an image area when image data includes an image having an area of a various size.
In this image forming device, preferably, the transverse cutting-position deciding means may take into account a top margin and a bottom margin for the image, which have been set before the formation of the image, in making a decision on the transverse cutting position, and the longitudinal cutting-position deciding means may take into account a left margin and a right margin for the image, which have been set before the formation of the image, in making a decision on the longitudinal cutting position. With this arrangement, adequate margins can be given to individual images.
A second image forming device according to the present invention is designed to form an image on a recording paper sheet on the basis of image data while moving the paper sheet to an image forming section. The second image forming device comprises:
paper sheet side edge detecting means for detecting the positions of two side edges of the paper sheet which are parallel with the paper sheet moving direction;
longitudinal cutting means for cutting the paper sheet in the same direction as a paper sheet moving direction by utilizing the moving power of the paper sheet, the longitudinal cutting means being mounted movably in a direction perpendicular to the paper sheet moving direction;
longitudinal cutting control means for moving and setting the longitudinal cutting means at a longitudinal cutting position; and
longitudinal cutting-position deciding means for deciding a longitudinal cutting position according to positional information about the two side edges of the paper sheet, obtained by the paper sheet side edge detecting means;
wherein the longitudinal cutting control means moves and sets the longitudinal cutting means at a longitudinal cutting position decided by the longitudinal cutting-position deciding means.
With this configuration, an appropriate position decided according to the width of a recording paper sheet used (an equally divided position, for example) can be set as the longitudinal cutting position with high accuracy.
A third image forming device according to the present invention is designed to form an image on a recording paper sheet on the basis of image data while moving the paper sheet to an image forming section. The third image forming device comprises:
paper sheet side edge detecting means for detecting the position of at least one of two side edges of the paper sheet which are parallel with a paper sheet moving direction;
transverse cutting means for cutting the paper sheet in a direction perpendicular to the paper sheet moving direction;
longitudinal cutting means for cutting the paper sheet in the same direction as the paper sheet moving direction by utilizing the moving power of the paper sheet, the longitudinal cutting means being mounted movably in a direction perpendicular to the paper sheet moving direction;
longitudinal cutting control means for moving and setting the longitudinal cutting means at a longitudinal cutting position;
size checking means for checking whether a paper sheet size specified for the image data is one of a plurality of standard paper sheet sizes;
table means having defined information about longitudinal and transverse cutting positions corresponding to the plurality of standard paper sheet sizes;
transverse cutting-position deciding means for obtaining information about a transverse cutting position by referring to the table means according to the standard size checked by the size checking means, and deciding a transverse cutting position according to the information about the transverse cutting position; and
longitudinal cutting-position deciding means for obtaining information about a longitudinal cutting position by referring to the table means according to the standard size checked by the size checking means, and deciding a longitudinal cutting position according to the information about longitudinal position and information about the paper sheet side edge detected by the paper sheet side edge detecting means;
wherein the longitudinal cutting control means moves and sets the longitudinal cutting means at a longitudinal cutting position decided by the longitudinal cutting-position deciding means.
With this configuration, standard sizes of paper sheet can be cut out of a roll paper sheet or a large-size cut-sheet.
A fourth image forming device according to the present invention is designed to form an image on a recording paper sheet on the basis of image data while moving the paper sheet to an image forming section. The forth image forming device comprises:
transverse cutting means for cutting the paper sheet in a direction perpendicular to a paper sheet moving direction;
longitudinal cutting means for cutting the paper sheet in the same direction as the paper sheet moving direction by utilizing the moving power of the paper sheet, the longitudinal cutting means being mounted movably in a direction perpendicular to the paper sheet moving direction;
image area detection means for obtaining information about an area of an image based on the image data;
paper sheet side edge detecting means for detecting the positions of two side edges of the paper sheet which are parallel with the paper sheet moving direction;
size checking means for checking whether a paper sheet size specified for the image data is any one of a plurality of standard paper sheet sizes; and
cutting-position deciding method selecting means for selecting any of a first cutting-position deciding method for deciding a longitudinal cutting position and a transverse cutting position according to image area information obtained by the image area detection means, a second cutting-position deciding method for deciding a longitudinal cutting position according to information about both side edges of the paper sheet obtained by the paper sheet side edge detecting means, and a third cutting-position deciding method for deciding a longitudinal cutting position and a transverse cutting position according to information about the standard paper sheet size obtained by the size checking means.
With this configuration, it becomes possible to selectively adopt a desired cutting method to meet the user""s request.
Note that when the second cutting-position deciding method is selected, any optional method for deciding a transverse cutting position can be selected.
In the respective image forming devices, the above-mentioned longitudinal cutting means can be located at a position decided by the longitudinal cutting-position deciding means during the image forming process, and a paper sheet can be cut in a longitudinal direction by utilizing the moving power of the paper sheet.